Electrochemical co-production of products with carbon-based reactant feed to anode

ABSTRACT

The present disclosure is a system and method for producing a first product from a first region of an electrochemical cell having a cathode and a second product from a second region of the electrochemical cell having an anode. The method may include a step of contacting the first region with a catholyte comprising carbon dioxide. The method may include another step of contacting the second region with an anolyte comprising a recycled reactant and at least one of an alkane, haloalkane, alkene, haloalkene, aromatic compound, haloaromatic compound, heteroaromatic compound or halo-heteroaromatic compound. Further, the method may include a step of applying an electrical potential between the anode and the cathode sufficient to produce a first product recoverable from the first region and a second product recoverable from the second region.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit under 35 U.S.C. §119(e) ofU.S. Provisional Application Ser. No. 61/720,670 filed Oct. 31, 2012,U.S. Provisional Application Ser. No. 61/703,158 filed Sep. 19, 2012 andU.S. Provisional Application Ser. No. 61/675,938 filed Jul. 26, 2012.Said U.S. Provisional Application Ser. No. 61/720,670 filed Oct. 31,2012, U.S. Provisional Application Ser. No. 61/703,158 filed Sep. 19,2012 and U.S. Provisional Application Ser. No. 61/675,938 filed Jul. 26,2012 are incorporated by reference in their entireties.

The present application also claims the benefit under 35 U.S.C. §119(e)of U.S. Provisional Application Ser. No. 61/703,229 filed Sep. 19, 2012,U.S. Provisional Application Ser. No. 61/703,175 filed Sep. 19, 2012,U.S. Provisional Application Ser. No. 61/703,231 filed Sep. 19, 2012,U.S. Provisional Application Ser. No. 61/703,232, filed Sep. 19, 2012,U.S. Provisional Application Ser. No. 61/703,234, filed Sep. 19, 2012,U.S. Provisional Application Ser. No. 61/703,238 filed Sep. 19, 2012,U.S. Provisional Application Ser. No. 61/703,187 filed Sep. 19, 2012.The U.S. Provisional Application Ser. No. 61/703,229 filed Sep. 19,2012, United States Provisional Application Ser. No. 61/703,175 filedSep. 19, 2012, U.S. Provisional Application Ser. No. 61/703,231 filedSep. 19, 2012, U.S. Provisional Application Ser. No. 61/703,232, filedSep. 19, 2012, U.S. Provisional Application Ser. No. 61/703,234, filedSep. 19, 2012, U.S. Provisional Application Ser. No. 61/703,238 filedSep. 19, 2012 and U.S. Provisional Application Ser. No. 61/703,187 filedSep. 19, 2012 are hereby incorporated by reference in their entireties.

The present application incorporates by reference U.S. patentapplication Ser. No. 13/724,339 filed on Dec. 21, 2012, U.S. patentapplication Ser. No. 13/724,878 filed on Dec. 21, 2012, U.S. patentapplication Ser. No. 13/724,231 filed on Dec. 21, 2012, U.S. patentapplication Ser. No. 13/724,807 filed on Dec. 21, 2012, U.S. patentapplication Ser. No. 13/724,996 filed on Dec. 21, 2012, U.S. patentapplication Ser. No. 13/724,719 filed on Dec. 21, 2012, U.S. patentapplication Ser. No. 13/724,082 filed on Dec. 21, 2012, and U.S. patentapplication Ser. No. 13/724,768 filed on Dec. 21, 2012, now U.S. Pat.No. 8,444,844 in their entireties.

TECHNICAL FIELD

The present disclosure generally relates to the field of electrochemicalreactions, and more particularly to methods and/or systems forelectrochemical co-production of chemicals with a carbon-based reactantfeed to anode.

BACKGROUND

The combustion of fossil fuels in activities such as electricitygeneration, transportation, and manufacturing produces billions of tonsof carbon dioxide annually. Research since the 1970s indicatesincreasing concentrations of carbon dioxide in the atmosphere may beresponsible for altering the Earth's climate, changing the pH of theocean and other potentially damaging effects. Countries around theworld, including the United States, are seeking ways to mitigateemissions of carbon dioxide.

A mechanism for mitigating emissions is to convert carbon dioxide intoeconomically valuable materials such as fuels and industrial chemicals.If the carbon dioxide is converted using energy from renewable sources,both mitigation of carbon dioxide emissions and conversion of renewableenergy into a chemical form that can be stored for later use will bepossible.

SUMMARY OF THE PREFERRED EMBODIMENTS

The present disclosure includes a system and method for producing afirst product from a first region of an electrochemical cell having acathode and a second product from a second region of the electrochemicalcell having an anode. The method may include a step of contacting thefirst region with a catholyte comprising carbon dioxide. The method mayinclude another step of contacting the second region with an anolytecomprising a recycled reactant and at least one of an alkane,haloalkane, alkene, haloalkene, aromatic compound, haloaromaticcompound, heteroaromatic compound or halo-heteroaromatic compound.Further, the method may include a step of applying an electricalpotential between the anode and the cathode sufficient to produce afirst product recoverable from the first region and a second productrecoverable from the second region.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not necessarily restrictive of the present disclosure. Theaccompanying drawings, which are incorporated in and constitute a partof the specification, illustrate subject matter of the disclosure.Together, the descriptions and the drawings serve to explain theprinciples of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The numerous advantages of the present disclosure may be betterunderstood by those skilled in the art by reference to the accompanyingfigures in which:

FIG. 1 is a block diagram of a system in accordance with an embodimentof the present disclosure;

FIG. 2A is a block diagram of a system in accordance with anotherembodiment of the present disclosure;

FIG. 2B is a block diagram of a system in accordance with an additionalembodiment of the present disclosure;

FIG. 3A is a block diagram of a system in accordance with an additionalembodiment of the present disclosure;

FIG. 3B is a block diagram of a system in accordance with an additionalembodiment of the present disclosure;

FIG. 4A is a block diagram of a system in accordance with an additionalembodiment of the present disclosure;

FIG. 4B is a block diagram of a system in accordance with an additionalembodiment of the present disclosure;

FIG. 5 is a flow diagram of a method of electrochemical co-production ofproducts in accordance with an embodiment of the present disclosure; and

FIG. 6 is a flow diagram of a method of electrochemical co-production ofproducts in accordance with another embodiment of the presentdisclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to the subject matter disclosed,which is illustrated in the accompanying drawings.

Referring generally to FIGS. 1-6, systems and methods of electrochemicalco-production of products with a carbon-based reactant feed to an anodeare disclosed. It is contemplated that the electrochemical co-productionof products may include a production of a first product, such asreduction of carbon dioxide to carbon-based products to include one,two, three, and four carbon chemicals, at a cathode side of anelectrochemical cell with co-production of a second product, such as anoxidized carbon-based product, at the anode of the electrochemical cellwhere the anolyte comprises a carbon-based reactant and a recycledreactant, where the recycled reactant is preferably a halide AX. AX maybe a compound where A is H, Li, Na, K, Cs, Mg, Ca, or other metal, orR₄P⁺, R₄N⁺—where each R is independently alkyl or aryl—or a cation; andX is F, Cl, Br, I, ClO4-, PF6-, BF4-, or an anion; and mixtures thereof.

A carbon-based reactant may include an oxidizable carbon compound.Carbon-based reactants may include, for example, methane, ethane,ethylene, benzene, toluene, xylene, ethylbenzene, propane, propene,butane, 1-butene, 2-butene, isobutane, ethyl acetate, propionitrile,methyl propionate, ethyl propionate, other alkanes, substituted alkanes,haloalkanes, alkenes, substituted alkenes, haloalkenes, aromatic,haloaromatic, heteroaromatic, and halo-heteroaromatic compounds.

Before any embodiments of the disclosure are explained in detail, it isto be understood that the embodiments may not be limited in applicationper the details of the structure or the function as set forth in thefollowing descriptions or illustrated in the figures. Differentembodiments may be capable of being practiced or carried out in variousways. Also, it is to be understood that the phraseology and terminologyused herein is for the purpose of description and should not be regardedas limiting. The use of terms such as “including,” “comprising,” or“having” and variations thereof herein are generally meant to encompassthe item listed thereafter and equivalents thereof as well as additionalitems. Further, unless otherwise noted, technical terms may be usedaccording to conventional usage. It is further contemplated that likereference numbers may describe similar components and the equivalentsthereof.

Referring to FIG. 1, a block diagram of a system 100 in accordance withan embodiment of the present disclosure is shown. System (or apparatus)100 generally includes an electrochemical cell (also referred as acontainer, electrolyzer, or cell) 102, a carbon-based reactant source104, a carbon dioxide source 106, a reactor 108, a first productextractor 110 and a first product 113, a second product extractor 112,second product 115, and an energy source 114.

Electrochemical cell 102 may be implemented as a divided cell. Thedivided cell may be a divided electrochemical cell and/or a dividedphotoelectrochemical cell. Electrochemical cell 102 may include a firstregion 116 and a second region 118. First region 116 and second region118 may refer to a compartment, section, or generally enclosed space,and the like without departing from the scope and intent of the presentdisclosure. First region 116 may include a cathode 122. Second region118 may include an anode 124. First region 116 may include a catholytewhereby carbon dioxide is dissolved in the catholyte. Second region 118may include an anolyte which may include a carbon-based reactant and arecycled reactant. A source of AX may be operably connected to secondregion 118. Energy source 114 may generate an electrical potentialbetween the anode 124 and the cathode 122. The electrical potential maybe a DC voltage. Energy source 114 may be configured to supply avariable voltage or constant current to electrochemical cell 102.Separator 120 may selectively control a flow of ions between the firstregion 116 and the second region 118. Separator 120 may include an ionconducting membrane or diaphragm material.

Electrochemical cell 102 is generally operational to reduce carbondioxide in the first region 116 to a first product 113 recoverable fromthe first region 116 while producing a second product 115 recoverablefrom the second region 118. Cathode 122 may reduce the carbon dioxideinto a first product 113 that may include one or more compounds.Examples of the first product 113 recoverable from the first region byfirst product extractor 110 may include CO, formic acid, formaldehyde,methanol, methane, oxalate, oxalic acid, glyoxylic acid, glyoxylate,glycolic acid, glycolate, glyoxal, glycolaldehyde, ethylene glycol,acetic acid, acetate, acetaldehyde, ethanol, ethane, ethylene, lacticacid, lactate, propanoic acid, propionate, acetone, isopropanol,1-propanol, 1,2-propylene glycol, propane, propylene, 1-butanol,2-butanone, 2-butanol, butane, butane, a carboxylic acid, a carboxylate,a ketone, an aldehyde, and an alcohol.

Carbon dioxide source 106 may provide carbon dioxide to the first region116 of electrochemical cell 102. In some embodiments, the carbon dioxideis introduced directly into the region 116 containing the cathode 122.It is contemplated that carbon dioxide source may include a source ofmultiple gases in which carbon dioxide has been filtered from themultiple gases.

First product extractor 110 may implement an organic product and/orinorganic product extractor. First product extractor 110 is generallyoperational to extract (separate) the first product 113 from the firstregion 116. The extracted first product 113 may be presented through aport of the system 100 for subsequent storage and/or consumption byother devices and/or processes.

The anode side of the reaction occurring in the second region 118 mayinclude a carbon-based reactant, which may be a gas phase, liquid phase,or solution phase reactant, and a recycled reactant supplied to thesecond region 118. The second product 115 recoverable from the secondregion 118 may be derived from a variety of oxidations such as theoxidation of an organic chemical of the carbon-based reactant to anotherorganic chemical product. Oxidations may be direct, such as theconversion of ethane to ethanol at the anode. They also may be indirect,such as conversion of ethane to ethanol utilizing a halogen produced atthe anode. Recycled reactant may include a hydrogen halide or halidesalt that may be recovered from the second product 115 via anotherreactor 108. For example, the recycled reactant may include AX where Ais H, Li, Na, K, Cs, Mg, Ca, or other metal, or R₄P⁺, R₄N⁺—where each Ris independently alkyl or aryl—or a cation; and X is F, Cl, Br, I, or ananion; and mixtures thereof. Examples are in the table below.

TABLE 1 Chemical Feed to Anode Oxidation Product(s) Methane Methanol,methyl bromide, chloroform Methanol Dibromomethane, formaldehyde, alphabromoethers, dialkoxy methane Ethane Ethyl Bromide, Ethanol, ethylene orother C2 chemicals Ethene (Ethylene) Vinyl chloride, vinyl bromide,tetrafluoroethylene Propane Propyl bromide, Propylene, Propanol or otherC3 chemicals Propene Allyl bromide, allyl alcohol, allyl halide, otherC3 chemicals Butane Butyl bromide, butene, butadiene, butanol, or otherC4 chemicals Butene Butadiene, halo-1-butenes, halo-2- butenes, otherhalo-C4 chemicals Isobutane Isobutylene, halo-isobutylenes, isobutylalcohols Ethylbenzene Styrene Ethyl acetate Vinyl acetate Methylpropionate, Ethyl Methyl acrylate, ethyl acrylate propionatePropionitrile Acrylonitrile Benzene Chlorobenzene, bromobenzene, PhenolToluene Benzyl alcohol, benzaldehyde, benzoic acid Xylene Terephthalicacid Alkanes Haloalkanes, polyhaloalkanes, perhaloalkanes HaloalkanesPolyhaloalkanes, perhaloalkanes Alkenes Haloalkenes, polyhaloalkenes,perhaloalkenes Haloalkenes Polyhaloalkenes, perhaloalkenes Halides (F⁻,Cl⁻, Br⁻, I⁻) Halogens (F₂, Cl₂, Br₂, I₂) Hydrogen halides (HF, HCl,HBr, Halogens (F₂, Cl₂, Br₂, I₂) HI)

Second product extractor 112 may extract the second product 115 from thesecond region 118. The extracted second product 115 may be presentedthrough a port of the system 100 for subsequent storage and/orconsumption by other devices and/or processes. It is contemplated thatfirst product extractor 110 and/or second product extractor 112 may beimplemented with electrochemical cell 102, or may be remotely locatedfrom the electrochemical cell 102. Additionally, it is contemplated thatfirst product extractor 110 and/or second product extractor 112 may beimplemented in a variety of mechanisms and to provide desired separationmethods, such as fractional distillation, without departing from thescope and intent of the present disclosure.

Furthermore, second product 115 may be presented to another reactor,such as a reactor 108, where a recycled reactant 117 is a byproduct of areaction of the second product 115 recovered from the second region 118of the electrochemical cell 102. A third product 119 produced by reactor108 as an additional byproduct of a reaction at reactor 108 may includean alcohol, alkene or various other types of compounds. Recycledreactant 117 may be recycled back to the second region 118 as an inputfeed to the second region 118 of electrochemical cell 102. It iscontemplated that an additional source of recycled reactant may befurther supplied as an input feed to the second region 118 of theelectrochemical cell 102 without departing from the scope and intent ofthe present disclosure.

Through the co-production of a first product 113 and a second product115, the overall energy requirement for making each of the first product113 and second product 115 may be reduced by 50% or more. In addition,electrochemical cell 102 may be capable of simultaneously producing twoor more products with high selectivity.

A preferred embodiment of the present disclosure may include productionof organic chemicals, such as carbon dioxide reduction products, at thecathode while simultaneously using a hydrogen halide or halide salt feedto the anode for use in the indirect oxidation of carbon-basedreactants. Referring to FIG. 2A, system 200 for co-production of acarbon dioxide reduction product 210 and an alcohol 218, through ahalogenated compound 212 is shown. The oxidation of AX 220 where A is H,Li, Na, K, Cs, Mg, Ca, or other metal, or R₄P⁺, R₄N⁺—where each R isindependently alkyl or aryl—or a cation; and X is F, Cl, Br, I, or ananion; and mixtures thereof (hereinafter generally referred as AX),produces protons and electrons that are utilized to reduce carbondioxide. A resulting halogen from the oxidation reaction at the secondregion 118, such as Br₂, may be reacted with a carbon-based reactant,such as ethane or propane, provided by carbon-based reactant source 104to selectively produce a halogenated compound 212. Halogenated compound212, such as bromoethane, may be isolated, or it may be supplied toreactor 214 that may react with water from water source 216 to producean alcohol 218, such as ethanol. While alcohol 218 is shown, it iscontemplated that various types of other products may also be producedvia reactor 214, such as an alkene. In one embodiment, a byproduct ofthe halogenation of an alkane supplied by carbon-based reactant source104 and subsequent conversion to an alcohol 218 is a recycled reactant220, such as hydrogen bromide.

AX 220 may be recycled back to the second region 118 of theelectrochemical cell 102 either as a pure anhydrous gas or in a liquidphase. The gas phase may be generally preferred in order to minimizeenergy requirements. Bromine or a similar halogen is thereby recycled,while a carbon dioxide reduction product 210 is produced at the firstregion 116 from CO₂. The halogen is thus used both to oxidizecarbon-based reactants, such as alkanes, alkenes and aromatic compounds,to a desired product and to transfer hydrogen ions or protons from thecarbon-based reactant to the first region for CO₂ reduction. Thecarbon-based reactant may serve as the primary hydrogen source for CO₂reduction. It is contemplated that an additional source of AX 222 may befurther supplied in addition to the recycled reactant AX 220 as an inputfeed to the second region 118 of the electrochemical cell 102 withoutdeparting from the scope and intent of the present disclosure.

System 200 of FIG. 2 may be employed with various types of carbon-basedreactants, including various types of alkanes, alkenes and aromaticcompounds to produce various types of products (first product and secondproduct) as desired and shown in an exemplary fashion in Table 1.Furthermore, a halogenated compound 212 may be further converted tovarious types of products, including a perhalocarbon, vinyl chloride,dichloroethane, allyl chloride, chlorophenol, bromobenzene, vinylbromide, vinyl fluoride, vinylidene fluoride, tetrafluoroethylene,hexafluoropropylene, difluoromethane, or pentafluoroethane. It isfurther contemplated that other types of products may be co-produced bythe anode and cathode of an electrochemical cell without departing fromthe scope and intent of the present disclosure.

Referring to FIG. 2B, a block diagram of a system 200 in accordance withan additional embodiment of the present disclosure. Similar to theembodiment shown in FIG. 2A, FIG. 2B is a block diagram of a system inaccordance with an additional embodiment of the present disclosurewherein carbon-based reactant source may supply an alkane, such asethane and the halogenated compound produced at second region 118 may bebromoethane 213. The carbon-dioxide reduction product may be acetic acid211. Bromoethane 213 may be supplied to reactor 214 and reacted withwater from water source 216 to produce HBr 221 which is recycled as aninput feed to the first region 118 and ethanol 219. In one embodiment ofthe disclosure, when the carbon dioxide reduction product is acetic acid211 and ethane is provided by carbon-based reactant source 104, then themolar ratios of the product may be 1 acetic acid: 4 ethanol becauseacetic acid production from CO₂ is an 8 electron process and ethanolfrom ethane is a two electron process. The mass ratios may be 1:3.

It is contemplated that reactions occurring at the first region 116 mayoccur in a catholyte which may include water, methanol, acetonitrile,propylene carbonate, ionic liquids, or other catholytes. The reactionsoccurring at the second region 118 may be in a gas phase, for instancein the case of gas phase reactant 118 such as methane or a hydrogenhalide. The reaction at the second region 118 may also occur in liquidphase, such as the case of a halide in solution.

In another embodiment, the second region 118 reaction may include anintroduction of gas phase benzene into anolyte with gaseous HBr, whereHBr is converted to bromine, which reacts with the benzene to producebromobenzene. A catalyst may be employed to promote the reaction, suchas an aluminum or iron-based catalyst, which could be incorporated intothe anode structure, especially if it is a high surface areacarbon-based material. More preferred, is to generate the bromine in thesecond region 118 from gaseous HBr, aqueous HBr, or NaBr, and then reactthe benzene as a liquid or as a gas with the bromine in a reactorcontaining, for example, an aluminum bromide or iron bromide catalyst ona carbon or inorganic support.

The bromobenzene may then be converted to phenols by a reaction with asodium hydroxide solution, similar to the hydrolysis of chlorobenzene,with NaOH under pressure. In addition, bromobenzene may be reacted withnitric acid to form p-nitro-bromobenzene, which can then be convertedafter several other chemical processing steps to p-methoxyphenol. Otherchemicals may be produced using bromobenzene as a raw starting material.

Many of the other reactions between bromine and the organics listed inTable 1 may also require catalysts or a radical initiator to achieve adesired bromination rate. These catalysts may be located in the anodestructure, or in the second region 118 where the bromine and organic arereacted to form a brominated intermediate compound. For example, acatalyst may be a soluble catalyst dissolved in a solution phase withinsecond region 118.

In addition, ultraviolet (UV) light has been shown to be an activatorfor the bromination reactions, where bromine forms a radical, and formsa chain reaction in brominating the organics. Designs in applying UVlight into the electrochemical cell 102 itself using quartz glass lightguides is possible, in addition to using glass piping in the productoutlet lines and in the chemical reactors where the bromine and organicare reacted. Different wavelength light can be used to moderate thereactions for better control, as well as the use of light emittingdiodes (LEDs) or lasers of differing light wavelengths are possible.

Referring to FIGS. 3A, 3B, 4A and 4B, block diagrams of systems 300, 400in accordance with additional embodiments of the present disclosure areshown. Systems 300, 400 provide additional embodiments to systems 100,200 of FIGS. 1-2 to co-produce a first product and second product.

Referring specifically to FIG. 3A, first region 116 of electrochemicalcell 102 may produce a first product of H₂ 310 which is combined withcarbon dioxide 332 in a reactor 330 which may perform a reverse watergas shift reaction. This reverse water gas shift reaction performed byreactor 330 may produce water 334 and carbon monoxide 336. Carbonmonoxide 336 along with H₂ 310 may be combined at reactor 338. Reactor338 may cause a reaction by utilizing H₂ 310 from the first region 116of the electrochemical cell 102, such as a Fischer-Tropsch-typereaction, to reduce carbon monoxide to a product 340. Product 340 mayinclude methane, methanol, hydrocarbons, glycols, olefins. Water 306,which may include a hydrogen halide, may be an additional productproduced by the first region 116 and may be recycled as an input feed tothe first region 116. Reactor 338 may also include transition metalssuch as iron, cobalt, and ruthenium as well as other transition metaloxides as catalysts, on inorganic support structures that may promotethe reaction of CO with hydrogen at lower temperatures and pressures.

Second region 118 may co-produce a halogenated compound 312, such asbromoethane, from a carbon-based reactant, such as an alkane 304 and ahydrogen halide recycled reactant 320, such as HBr. Halogenated compound312 may be isolated, or may be supplied to a dehydrohalogenation reactor314 to generate byproducts such as an alkene 318, for example, ethyleneand a hydrogen halide recycled reactant 320, such as HBr, which isrecycled back as an input feed to the second region 118. It iscontemplated that alkane 304 may be other types of carbon-basedreactants, including various types of alkanes, alkenes or aromaticcompounds while halogenated compound 312 may also refer to any type ofhalogenated compound that may be supplied to a dehydrohalogenationreactor 314 to produce various types of alkenes, alcohols, glycols orolefins without departing from the scope or intent of the presentdisclosure. Referring to FIG. 3B, it is contemplated that second region118 may co-produce a bromoethane 313, from a carbon-based reactant, suchas an ethane 305. Bromoethane 313 may be isolated, or may be supplied toa dehydrohalogenation reactor 314 to generate products such as ethylene319 and HBr 321 which is recycled back as an input feed to the secondregion 118.

Referring to FIG. 4A, first region 116 of electrochemical cell 102 mayproduce a first product of carbon monoxide 410 which is combined withwater 432 in a reactor 430 which may perform a water gas shift reaction.This water gas shift reaction performed by reactor 430 may producecarbon dioxide 434 and H₂ 436. Carbon monoxide 410 and H₂ 436 may becombined at reactor 438. Reactor 438 may cause a reaction, such as aFischer-Tropsch-type reaction, to reduce carbon monoxide to a product440. Product 440 may include methane, methanol, hydrocarbons, glycols,olefins by utilizing H₂ 436 from the water gas shift reaction. Carbondioxide 434 may be a byproduct of water gas shift reaction of reactor430 and may be recycled as an input feed to the first region 116. Water406, which may include a hydrogen halide, may be an additional productproduced by the first region 116 and may be recycled as another inputfeed to the first region 116. Reactor 438 may also include transitionmetals such as iron and copper as well as other transition metal oxidesas catalysts, on inorganic support structures that may promote thereaction of CO with hydrogen at lower temperatures and pressures.

Second region 118 of electrochemical cell 102 may co-produce ahalogenated compound 412, such as bromoethane, from a carbon-basedreactant such as an alkane 404 and a hydrogen halide recycled reactant420, such as HBr. Halogenated compound 412, may be isolated, or may besupplied to a dehydrohalogenation reactor 414 to generate an alkene 418,such as ethylene and a hydrogen halide recycled reactant 420, such asHBr, which is recycled back as an input feed to the second region 118.It is contemplated that carbon-based reactant, such as an alkane 404,may be any type of alkane, alkene or aromatic compound while halogenatedcompound may also refer to any type of halogenated compound that may besupplied to a dehydrohalogenation reactor 414 to produce various typesof alcohols, glycols or olefins without departing from the scope orintent of the present disclosure.

Referring to FIG. 4B, it is contemplated that second region 118 mayco-produce a bromoethane 413, from a carbon-based reactant, such as anethane 405. Bromoethane 413 may be isolated, or may be supplied to adehydrohalogenation reactor 414 to generate products such as ethylene419 and HBr 421 which is recycled back as an input feed to the secondregion 118.

Referring to FIG. 5 a flow diagram of a method 500 of electrochemicalco-production of products in accordance with an embodiment of thepresent disclosure is shown. It is contemplated that method 500 may beperformed by system 100 and system 200 as shown in FIGS. 1-2. Method 500may include producing a first product from a first region of anelectrochemical cell having a cathode and a second product from a secondregion of the electrochemical cell having an anode.

Method 500 of electrochemical co-production of products may include astep of contacting a first region of an electrochemical cell with acatholyte including carbon dioxide 510. Next, method 500 may includecontacting a second region of an electrochemical cell with an anolyteincluding a recycled reactant and at least one of an alkane, haloalkane,alkene, haloalkene, aromatic compound, haloaromatic compound,heteroaromatic compound or halo-heteroaromatic compound 520. Method 500may further include applying an electrical potential between the anodeand the cathode sufficient to produce a first product recoverable fromthe first region and a second product recoverable from the second region530. Advantageously, a first product produced at the first region may berecoverable from the first region and a second product produced at thesecond region may be recoverable from the second region.

Referring to FIG. 6, a flow diagram of a method 600 of electrochemicalco-production of products in accordance with another embodiment of thepresent disclosure is shown. It is contemplated that method 600 may beperformed by system 100 and system 200 as shown in FIGS. 1-2. Method 600may include steps for producing a first product from a first region ofan electrochemical cell having a cathode and a second product from asecond region of the electrochemical cell having an anode.

Method 600 may include a step of receiving a feed of carbon dioxide atthe first region of the electrochemical cell 610. Method 600 may furtherinclude contacting the first region with a catholyte comprising carbondioxide 620. Next, method 600 may include receiving a feed of a recycledreactant and at least one alkane at the second region of theelectrochemical cell, the recycled reactant is AX where X is selectedfrom the group consisting of F, Cl, Br, I and mixtures thereof, and A isselected from the group consisting of H, Li, Na, K, Cs and mixturesthereof 630. Method 600 may further include contacting the second regionwith an anolyte comprising the recycled reactant and the at least onealkane 640. Method 600 may further include applying an electricalpotential between the anode and the cathode sufficient to produce afirst product recoverable from the first region and a second productrecoverable from the second region 650.

It is contemplated that a receiving feed may include various mechanismsfor receiving a supply of a product, whether in a continuous, nearcontinuous or batch portions.

It is further contemplated that the structure and operation of theelectrochemical cell 102 may be adjusted to provide desired results. Forexample, the electrochemical cell 102 may operate at higher pressures,such as pressure above atmospheric pressure which may increase currentefficiency and allow operation of the electrochemical cell at highercurrent densities.

Additionally, the cathode 122 and anode 124 may include a high surfacearea electrode structure with a void volume which may range from 30% to98%. The electrode void volume percentage may refer to the percentage ofempty space that the electrode is not occupying in the total volumespace of the electrode. The advantage in using a high void volumeelectrode is that the structure has a lower pressure drop for liquidflow through the structure. The specific surface area of the electrodebase structure may be from 2 cm²/cm³ to 500 cm²/cm³ or higher. Theelectrode specific surface area is a ratio of the base electrodestructure surface area divided by the total physical volume of theentire electrode. It is contemplated that surface areas also may bedefined as a total area of the electrode base substrate in comparison tothe projected geometric area of the current distributor/conductor backplate, with a preferred range of 2×to 1000× or more. The actual totalactive surface area of the electrode structure is a function of theproperties of the electrode catalyst deposited on the physical electrodestructure which may be 2 to 1000 times higher in surface area than thephysical electrode base structure.

Cathode 122 may be selected from a number of high surface area materialsto include copper, stainless steels, transition metals and their alloysand oxides, carbon, and silicon, which may be further coated with alayer of material which may be a conductive metal or semiconductor. Thebase structure of cathode 122 may be in the form of fibrous,reticulated, or sintered powder materials made from metals, carbon, orother conductive materials including polymers. The materials may be avery thin plastic screen incorporated against the cathode side of themembrane to prevent the membrane 120 from directly touching the highsurface area cathode structure. The high surface area cathode structuremay be mechanically pressed against a cathode current distributorbackplate, which may be composed of material that has the same surfacecomposition as the high surface area cathode.

In addition, cathode 122 may be a suitable conductive electrode, such asAl, Au, Ag, Bi, C, Cd, Co, Cr, Cu, Cu alloys (e.g., brass and bronze),Ga, Hg, In, Mo, Nb, Ni, NiCo₂O₄, Ni alloys (e.g., Ni 625, NiHX), Ni—Fealloys, Pb, Pd alloys (e.g., PdAg), Pt, Pt alloys (e.g., PtRh), Rh, Sn,Sn alloys (e.g., SnAg, SnPb, SnSb), Ti, V, W, Zn, stainless steel (SS)(e.g., SS 2205, SS 304, SS 316, SS 321), austenitic steel, ferriticsteel, duplex steel, martensitic steel, Nichrome (e.g., NiCr 60:16 (withFe)), elgiloy (e.g., Co—Ni—Cr), degenerately doped p-Si, degeneratelydoped p-Si:As, degenerately doped p-Si:B, degenerately doped n-Si,degenerately doped n-Si:As, and degenerately doped n-Si:B. These metalsand their alloys may also be used as catalytic coatings on the variousmetal substrates. Other conductive electrodes may be implemented to meetthe criteria of a particular application. For photoelectrochemicalreductions, cathode 122 may be a p-type semiconductor electrode, such asp-GaAs, p-GaP, p-InN, p-InP, p-CdTe, p-GalnP₂ and p-Si, or an n-typesemiconductor, such as n-GaAs, n-GaP, n-InN, n-InP, n-CdTe, n-GalnP₂ andn-Si. Other semiconductor electrodes may be implemented to meet thecriteria of a particular application including, but not limited to, CoS,MoS₂, TiB, WS₂, SnS, Ag₂S, CoP₂, Fe₃P, Mn₃P₂, MoP, Ni₂Si, MoSi₂, WSi2,CoSi₂, Ti₄O₇, SnO₂, GaAs, GaSb, Ge, and CdSe.

Catholyte may include a pH range from 1 to 12, preferably from pH 4 topH 10. The selected operating pH may be a function of any catalystsutilized in operation of the electrochemical cell 102. Preferably,catholyte and catalysts may be selected to prevent corrosion at theelectrochemical cell 102. Catholyte may include homogeneous catalysts.Homogeneous catalysts are defined as aromatic heterocyclic amines andmay include, but are not limited to, unsubstituted and substitutedpyridines and imidazoles. Substituted pyridines and imidazoles mayinclude, but are not limited to mono and disubstituted pyridines andimidazoles. For example, suitable catalysts may include straight chainor branched chain lower alkyl (e.g., C1-C10) mono and disubstitutedcompounds such as 2-methylpyridine, 4-tertbutyl pyridine, 2,6dimethylpyridine (2,6-lutidine); bipyridines, such as 4,4′-bipyridine;amino-substituted pyridines, such as 4-dimethylamino pyridine; andhydroxyl-substituted pyridines (e.g., 4-hydroxy-pyridine) andsubstituted or unsubstituted quinoline or isoquinolines. The catalystsmay also suitably include substituted or unsubstituted dinitrogenheterocyclic amines, such as pyrazine, pyridazine and pyrimidine. Othercatalysts generally include azoles, imidazoles, indoles, oxazoles,thiazoles, substituted species and complex multi-ring amines such asadenine, pterin, pteridine, benzimidazole, phenonthroline and the like.

The catholyte may include an electrolyte. Catholyte electrolytes mayinclude alkali metal bicarbonates, carbonates, sulfates, phosphates,borates, and hydroxides. The electrolyte may comprise one or more ofNa₂SO₄, KCl, NaNO₃, NaCl, NaF, NaClO₄, KClO₄, K₂SiO₃, CaCl₂, aguanidinium cation, an H cation, an alkali metal cation, an ammoniumcation, an alkylammonium cation, a tetraalkyl ammonium cation, a halideanion, an alkyl amine, a borate, a carbonate, a guanidinium derivative,a nitrite, a nitrate, a phosphate, a polyphosphate, a perchlorate, asilicate, a sulfate, and a hydroxide. In one embodiment, bromide saltssuch as NaBr or KBr may be preferred.

The catholyte may further include an aqueous or non-aqueous solvent. Anaqueous solvent may include greater than 5% water. A non-aqueous solventmay include as much as 5% water. A solvent may contain one or more ofwater, a protic solvent, or an aprotic polar solvent. Representativesolvents include methanol, ethanol, acetonitrile, propylene carbonate,ethylene carbonate, dimethyl carbonate, diethyl carbonate,dimethylsulfoxide, dimethylformamide, acetonitrile, acetone,tetrahydrofuran, N,N-dimethylacetamide, dimethoxyethane, diethyleneglycol dimethyl ester, butyronitrile, 1,2-difluorobenzene,γ-butyrolactone, N-methyl-2-pyrrolidone, sulfolane, 1,4-dioxane,nitrobenzene, nitromethane, acetic anhydride, ionic liquids, andmixtures thereof.

In one embodiment, a catholyte/anolyte flow rate may include acatholyte/anolyte cross sectional area flow rate range such as 2-3,000gpm/ft² or more (0.0076-11.36 m³/m²). A flow velocity range may be 0.002to 20 ft/sec (0.0006 to 6.1 m/sec). Operation of the electrochemicalcell catholyte at a higher operating pressure allows more dissolvedcarbon dioxide to dissolve in the aqueous solution. Typically,electrochemical cells can operate at pressures up to about 20 to 30 psigin multi-cell stack designs, although with modifications, theelectrochemical cells may operate at up to 100 psig. The electrochemicalcell may operate anolyte at the same pressure range to minimize thepressure differential on a separator 120 or membrane separating the tworegions. Special electrochemical designs may be employed to operateelectrochemical units at higher operating pressures up to about 60 to100 atmospheres or greater, which is in the liquid CO₂ and supercriticalCO₂ operating range.

In another embodiment, a portion of a catholyte recycle stream may beseparately pressurized using a flow restriction with backpressure orusing a pump, with CO₂ injection, such that the pressurized stream isthen injected into the catholyte region of the electrochemical cellwhich may increase the amount of dissolved CO₂ in the aqueous solutionto improve the conversion yield. In addition, micro-bubble generation ofcarbon dioxide can be conducted by various means in the catholyterecycle stream to maximize carbon dioxide solubility in the solution.

Catholyte may be operated at a temperature range of −10 to 95° C., morepreferably 5-60° C. The lower temperature will be limited by thecatholytes used and their freezing points. In general, the lower thetemperature, the higher the solubility of CO₂ in an aqueous solutionphase of the catholyte, which would help in obtaining higher conversionand current efficiencies. The drawback is that the operatingelectrochemical cell voltages may be higher, so there is an optimizationthat would be done to produce the chemicals at the lowest operatingcost. In addition, the catholyte may require cooling, so an externalheat exchanger may be employed, flowing a portion, or all, of thecatholyte through the heat exchanger and using cooling water to removethe heat and control the catholyte temperature.

Anolyte operating temperatures may be in the same ranges as the rangesfor the catholyte, and may be in a range of 0° C. to 95° C. In addition,the anolyte may require cooling, so an external heat exchanger may beemployed, flowing a portion, or all, of the anolyte through the heatexchanger and using cooling water to remove the heat and control theanolyte temperature.

Electrochemical cells may include various types of designs. Thesedesigns may include zero gap designs with a finite or zero gap betweenthe electrodes and membrane, flow-by and flow-through designs with arecirculating catholyte electrolyte utilizing various high surface areacathode materials. The electrochemical cell may include floodedco-current and counter-current packed and trickle bed designs with thevarious high surface area cathode materials. Also, bipolar stack celldesigns and high pressure cell designs may also be employed for theelectrochemical cells.

Anode electrodes may be the same as cathode electrodes or different.Anode 124 may include electrocatalytic coatings applied to the surfacesof the base anode structure. Anolytes may be the same as catholytes ordifferent. Anolyte electrolytes may be the same as catholyteelectrolytes or different. Anolyte may comprise solvent. Anolyte solventmay be the same as catholyte solvent or different. For example, for HBr,acid anolytes, and oxidizing water generating oxygen, the preferredelectrocatalytic coatings may include precious metal oxides such asruthenium and iridium oxides, as well as platinum and gold and theircombinations as metals and oxides on valve metal substrates such astitanium, tantalum, zirconium, or niobium. For bromine and iodine anodechemistry, carbon and graphite are particularly suitable for use asanodes. Polymeric bonded carbon material may also be used. For otheranolytes, comprising alkaline or hydroxide electrolytes, anodes mayinclude carbon, cobalt oxides, stainless steels, transition metals, andtheir alloys and combinations. High surface area anode structures thatmay be used which would help promote the reactions at the anodesurfaces. The high surface area anode base material may be in areticulated form composed of fibers, sintered powder, sintered screens,and the like, and may be sintered, welded, or mechanically connected toa current distributor back plate that is commonly used in bipolarelectrochemical cell assemblies. In addition, the high surface areareticulated anode structure may also contain areas where additionalapplied catalysts on and near the electrocatalytic active surfaces ofthe anode surface structure to enhance and promote reactions that mayoccur in the bulk solution away from the anode surface such as thereaction between bromine and the carbon based reactant being introducedinto the anolyte. The anode structure may be gradated, so that thedensity of the may vary in the vertical or horizontal direction to allowthe easier escape of gases from the anode structure. In this gradation,there may be a distribution of particles of materials mixed in the anodestructure that may contain catalysts, such as metal halide or metaloxide catalysts such as iron halides, zinc halides, aluminum halides,cobalt halides, for the reactions between the bromine and thecarbon-based reactant. For other anolytes comprising alkaline, orhydroxide electrolytes, anodes may include carbon, cobalt oxides,stainless steels, and their alloys and combinations.

Separator 120, also referred to as a membrane, between a first region118 and second region 118, may include cation ion exchange typemembranes. Cation ion exchange membranes which have a high rejectionefficiency to anions may be preferred. Examples of such cation ionexchange membranes may include perfluorinated sulfonic acid based ionexchange membranes such as DuPont Nafion® brand unreinforced types N117and N120 series, more preferred PTFE fiber reinforced N324 and N424types, and similar related membranes manufactured by Japanese companiesunder the supplier trade names such as AGC Engineering (Asahi Glass)under their trade name Flemion®. Other multi-layer perfluorinated ionexchange membranes used in the chlor alkali industry may have a bilayerconstruction of a sulfonic acid based membrane layer bonded to acarboxylic acid based membrane layer, which efficiently operates with ananolyte and catholyte above a pH of about 2 or higher. These membranesmay have a higher anion rejection efficiency. These are sold by DuPontunder their Nafion® trademark as the N900 series, such as the N90209,N966, N982, and the 2000 series, such as the N2010, N2020, and N2030 andall of their types and subtypes. Hydrocarbon based membranes, which aremade from of various cation ion exchange materials can also be used ifthe anion rejection is not as desirable, such as those sold by Sybronunder their trade name Ionac®, AGC Engineering (Asahi Glass) under theirSelemion® trade name, and Tokuyama Soda, among others on the market.Ceramic based membranes may also be employed, including those that arecalled under the general name of NASICON (for sodium super-ionicconductors) which are chemically stable over a wide pH range for variouschemicals and selectively transports sodium ions, the composition isNa₁+xZr₂Si_(x)P₃−xO₁₂, and well as other ceramic based conductivemembranes based on titanium oxides, zirconium oxides and yttrium oxides,and beta aluminum oxides. Alternative membranes that may be used arethose with different structural backbones such as polyphosphazene andsulfonated polyphosphazene membranes in addition to crown ether basedmembranes. Preferably, the membrane or separator is chemically resistantto the anolyte and catholyte and operates at temperatures of less than600 degrees C., and more preferably less than 500 degrees C.

A rate of the generation of reactant formed in the anolyte compartmentfrom the anode reaction, such as the oxidation of HBr to bromine, iscontemplated to be proportional to the applied current to theelectrochemical cell 102. The rate of the input or feed of thecarbon-based reactant, for example ethane, into the anolyte region 118should then be fed in proportion to the generated reactant. The molarratio of the carbon-based reactant to the generated anode reactant, suchas Br₂, may be in the range of 100:1 to 1:10, and more preferably in therange of 50:1 to 1:5. The anolyte product output in this range can besuch that the output stream contains little or no free bromine in theproduct output to the second product extractor 112, or it may containunreacted bromine. The operation of the extractor 112 and its selectedseparation method, for example fractional distillation, the actualproducts produced, and the selectivity of the wanted reaction woulddetermine the optimum molar ratio of the carbon-based reactant to thegenerated reactant in the anode compartment. Any of the unreactedcomponents would be recycled to the second region 118.

Similarly, a rate of the generation of the formed electrochemical carbondioxide reduction product 210, such as CO, is contemplated to beproportional to the applied current to the electrochemical cell 102. Therate of the input or feed of the carbon dioxide source 106 into thefirst region 116 should be fed in a proportion to the applied current.The cathode reaction efficiency would determine the maximum theoreticalformation in moles of the carbon dioxide reduction product 210. It iscontemplated that the ratio of carbon dioxide feed to the theoreticalmoles of potentially formed carbon dioxide reduction product would be ina range of 100:1 to 2:1, and preferably in the range of 50:1 to 5:1,where the carbon dioxide is in excess of the theoretical required forthe cathode reaction. The carbon dioxide excess would then be separatedin the extractor 110 and recycled back to the first region 116.

In the present disclosure, the methods disclosed may be implemented assets of instructions or software readable by a device. Further, it isunderstood that the specific order or hierarchy of steps in the methodsdisclosed are examples of exemplary approaches. Based upon designpreferences, it is understood that the specific order or hierarchy ofsteps in the method can be rearranged while remaining within thedisclosed subject matter. The accompanying method claims presentelements of the various steps in a sample order, and are not necessarilymeant to be limited to the specific order or hierarchy presented.

It is believed that the present disclosure and many of its attendantadvantages will be understood by the foregoing description, and it willbe apparent that various changes may be made in the form, constructionand arrangement of the components without departing from the disclosedsubject matter or without sacrificing all of its material advantages.The form described is merely explanatory, and it is the intention of thefollowing claims to encompass and include such changes.

What is claimed is:
 1. A method for producing a first product from afirst region of an electrochemical cell having a cathode and a secondproduct from a second region of the electrochemical cell having ananode, the method comprising the steps of: contacting the first regionwith a catholyte comprising carbon dioxide; contacting the second regionwith an anolyte comprising a recycled reactant and at least one of analkane, haloalkane, alkene, haloalkene, aromatic compound, haloaromaticcompound, heteroaromatic compound or halo-heteroaromatic compound, therecycled reactant includes a halide salt; and applying an electricalpotential between the anode and the cathode sufficient to produce thefirst product recoverable from the first region and the second productrecoverable from the second region.
 2. The method according to claim 1,wherein the halide salt is AX where A is selected from the groupconsisting of Li, Na, K and Cs and X is selected from the groupconsisting of F, Cl, Br and I.
 3. The method according to claim 1,wherein the second product includes a halogenated compound.
 4. Themethod according to claim 3, further comprising: removing thehalogenated compound from the second region; and converting thehalogenated compound to a different compound.
 5. The method according toclaim 1, wherein the catholyte further comprises a solvent selected fromthe group consisting of propylene carbonate, water, methanol, ethanol,acetonitrile, dimethylformamide, dimethylsulfoxide, and pyrrolidinone.6. The method according to claim 1, wherein the catholyte and theanolyte are separated by an ion permeable barrier that operates at atemperature less than 600 degrees C.
 7. The method according to claim 6,wherein the ion permeable barrier includes one of a polymeric orinorganic ceramic-based ion permeable barrier.
 8. The method accordingto claim 1, wherein the catholyte is liquid phase and the anolyte is gasphase.
 9. A method for producing a first product from a first region ofan electrochemical cell having a cathode and a second product from asecond region of the electrochemical cell having an anode, the methodcomprising the steps of: contacting the first region with a catholytecomprising carbon dioxide; contacting the second region with an anolytecomprising a recycled reactant and at least one of an alkane,haloalkane, alkene, haloalkene, aromatic compound, haloaromaticcompound, heteroaromatic compound or halo-heteroaromatic compound, therecycled reactant includes a halide salt; applying an electricalpotential between the anode and the cathode sufficient to produce thefirst product recoverable from the first region and the second productrecoverable from the second region, wherein the second product includesa halogenated compound; removing the halogenated compound from thesecond region; and converting the halogenated compound to a differentcompound.
 10. The method according to claim 9, wherein the catholytefurther comprises a solvent selected from the group consisting ofpropylene carbonate, water, methanol, ethanol, acetonitrile,dimethylformamide, dimethylsulfoxide, and pyrrolidinone.
 11. The methodaccording to claim 9, wherein the catholyte and the anolyte areseparated by an ion permeable barrier that operates at a temperatureless than 600 degrees C.
 12. The method according to claim 11, whereinthe ion permeable barrier includes one of a polymeric or inorganicceramic-based ion permeable barrier.
 13. The method according to claim9, wherein the catholyte is liquid phase and the anolyte is gas phase.14. The method according to claim 9, wherein the halide salt is AX whereA is selected from the group consisting of Li, Na, K and Cs and X isselected from the group consisting of F, Cl, Br and I.
 15. A method forproducing a first product from a first region of an electrochemical cellhaving a cathode and a second product from a second region of theelectrochemical cell having an anode, the method comprising the stepsof: contacting the first region with a catholyte comprising carbondioxide; contacting the second region with an anolyte comprising arecycled reactant and at least one of an alkane, haloalkane, alkene,haloalkene, aromatic compound, haloaromatic compound, heteroaromaticcompound or halo-heteroaromatic compound; and applying an electricalpotential between the anode and the cathode sufficient to produce thefirst product recoverable from the first region and the second productrecoverable from the second region, wherein the catholyte is liquidphase and the anolyte is gas phase.
 16. The method of claim 15, whereinthe recycled reactant includes a halide salt.
 17. The method accordingto claim 16, wherein the halide salt is AX where A is selected from agroup consisting of Li, Na, K and Cs and X is selected from the groupconsisting of F, Cl, Br and I.
 18. The method according to claim 16,wherein the second product includes a halogenated compound.
 19. Themethod according to claim 18, further comprising: removing thehalogenated compound from the second region; and converting thehalogenated compound to a different compound.
 20. The method accordingto claim 15, wherein the catholyte further comprises a solvent selectedfrom the group consisting of propylene carbonate, water, methanol,ethanol, acetonitrile, dimethylformamide, dimethylsulfoxide, andpyrrolidinone.
 21. The method according to claim 15, wherein thecatholyte and the anolyte are separated by an ion permeable barrier thatoperates at a temperature less than 600 degrees C.
 22. The methodaccording to claim 21, wherein the ion permeable barrier includes one ofa polymeric or inorganic ceramic-based ion permeable barrier.